Feasibility of UVC-LED/H₂O₂ advanced oxidation processes as a hybrid water treatment system uniting secondary battery and microbial fuel cell

An innovative hybrid water treatment system consisting of an ultraviolet C light-emitting diode sequentially connected to a secondary battery and microbial fuel cells was developed and systematically optimized via an electrochemical performance test. According to standardized bio-dosimetry, the generated ultraviolet intensity powered by a pre-charged battery was determined to be 2.3×10⁻¹ μW cm⁻². The quantified UV intensity was used in calculating the fundamental kinetic parameters for the inactivation of microbial entities and the degradation of organic pollutants during UVC-LED and UVC-LED/H₂O₂ treatment processes. The fluence-based first-order rate constants were 1.07 and 2.43 cm²/mJ for Escherichia coli and 0.10 and 0.18 cm²/mJ for MS-2 bacteriophage, respectively. The study detected 2.76–8.00×10⁻¹⁶ M hydroxyl radicals at steady-state during UVC-LED/H₂O₂ treatment with 0.3–1 mM H₂O₂. The second-order rate constant for atrazine during UVC-LED/H₂O₂ treatment was 1.90×10⁹ M⁻¹ s⁻¹ according to linear regression analysis of atrazine elimination over •OH exposure. This comprehensive investigation expands the application of microbial electrochemical systems in water treatment, providing a fundamental kinetic dataset for quantifying and predicting the microbial and (persistent) organic pollutants abatement.